The proposed work involves the further development of a new quantitative and imaging ultrasonic technique which encode amplitude information following frequency band filtering. It is planned also to perform theoretical studies, computer simulations and experimental work which will result in the creation of further new innovative types of image and quantitative data based on instantaneous frequency and amplitude content of backscattered ultrasound. The experimental work will involve the utilization of two different experimental systems; an extremely versatile laboratory system will be employed for a variety of studies of phantoms with known acoustic and scattering characteristics. A second dedicated ultrasound machine adapted to acquire RF data from tissue region of interest in the real time ultrasonic image will be employed in clinical studies. It is also planned to adapt a more state of the art clinical scanner for the acquisition of RF data in further clinical studies. The phantom studies will employ phantoms with differing types and concentrations and distribution scatterers to observe the effects of these variables on the frequency and amplitude content of received ultrasonic waveform data, and develop optimal methods of differentiating such phantoms based on their scattering characteristics. Extensive work will be performed to separate the effects of the frequency dependence of backscattering of ultrasound from the frequency dependent attenuation and diffraction effects. This will involve two basic approaches: 1) investigation of the possibility of "correction" of the filtered amplitude distributions on the basis of depth range, or overall system gain 2) measurement of the frequency- dependent attenuation of regions overlying regions to be characterized on the basis of their scattering characteristics. In clinical studies it is planned to scan normal livers and livers of patients with a wide range of diffuse liver diseases. A major goal will be a determination of whether the extent of hepatic fibrosis may be characterized noninvasively by ultrasound. The second major clinical project will involve the acquisition of RF data from spleens of patients prior to staging laparotomy to determine the possibility of non-invasive determination of splenic involvement with lymphoma. Limited in vitro studies of liver specimens are proposed to obtain the best possible ultrasonic/histologic correlation.